The 'Good News' excerpt:
"Scientists have found and manipulated body chemistry linked to the aging of muscles and were able to turn back the clock on old human muscle, restoring its ability to repair and rebuild itself, they said today."
Of course, there's never only good news
"Importantly, the research also found evidence that aging muscles need to be kept in shape, because long periods of atrophy are more challenging to overcome. Older muscles do not respond as well to sudden bouts of exercise, the scientists discovered. And rather than building muscle, an older person can generate scar tissue upon, say, lifting weights after long periods of inactivity."
See the article for more/specifics.
That there may someday be a therapy to keep muscles 'young' is interesting.